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Karst in the Canadian Rockies

Dezaiko Plateau

Karst landscapes are found around the world wherever there is water-soluble bedrock, but they differ in appearance depending on the amount of rainfall, the chemical aggressiveness of the water, the quality of the soluble bedrock, and a number of other local factors. In the case of the Rocky Mountains, successive periods of glaciation have in large measure destroyed older karst landscapes and portions of the caves below. But where the ice was relatively stationary, karst landscapes actually formed beneath the ice which, as it melted, supplied the plentiful water that slowly dissolved the limestone beneath it. These karst landscapes are seen today on high mountain benches where the ice has disappeared, and continue to develop under the influence of rain and snow.

Karst landscapes in the Canadian Rockies are alpine karst, with similarities to other high-altitude mountainous limestone regions. Alpine karst is of two distinctive forms; undulating knolls and dips, and flat expanses known as limestone pavements. In the valleys below these landscapes one might expect to find karst springs, where water emerges from the bedrock after its underground journey. Of course, this is only the visible surface of the picture, as karst landscapes are three-dimensional and include caves and other features within the bedrock itself.

Looking closer at karst landscapes one finds smaller features, sometimes called surface karst. These take on a variety of shapes and sizes, but all are caused by water. Sometimes their shaping occurs on exposed surfaces, sometimes under mantles of soil. As water dissolves pockets or channels in the rock, these in turn serve as collection points for more water, resulting in deepening of channels while leaving the high-points relatively untouched. Small channel features caused by rainwater or snowmelt are called karren, of which there are several types, including the classic rillenkarren which forms miniature mountain-ridges and valleys on sloped surfaces.

Surface karst features are formed by the same natural forces that create and shape underground caves. In a sense their unique shapes are the transition between the two, and remind us that the surface and underground are not separate, but all part of the same natural environment.